This project will examine the complex relationships between race, diabetes self-management (including self-monitoring of blood glucose and diabetes drug therapy), glycemic control, and diabetes complications in a managed care setting over a nine-year period. African Americans with diabetes are less likely to be in glycemic control, a major risk factor for development of complications, including nephropathy, retinopathy, and peripheral vascular disease. Randomized controlled trials suggest that diabetes self-management including patient education, drug therapy, changes in diet, and regular exercise can improve glycemic control in the African American population. However, there is little epidemiological evidence regarding the role of race/ethnicity as a determinant of adherence to recommended diabetes self-management practices, or regarding the relationship between self-management, glycemic control, and subsequent clinical outcomes. Further, previous studies of race and diabetes self-management have been limited by short study periods, inadequate sample size, and reliance on self-reported measures of self-monitoring of blood glucose. The clinical setting for this study is Harvard Vanguard Medical Associates (HVMA), a large multi-site, multi-specialty group affiliated with Harvard Pilgrim Health Care. HVMA consists of 14 health centers serving over 300,000 people in the Boston area. We will use an open cohort design to enroll all adult (l8 years) patients between 1991 and 1999 who have 24 months or more of uninterrupted enrollment in HVMA following ascertainment of non-gestational diabetes, defined by (1) hospital discharge diagnosis of diabetes mellitus, (2) outpatient diagnoses of diabetes mellitus, HbAlc lab test result 8.0, or use of a diabetes drug (insulin, sulfonylurea, or metformin). We estimate that the cohort will include approximately 1,800 adults identified as African American and 5,000 identified as Caucasian. Access to HVMA computerized medical records, hospital emergency room and inpatient claims, lab, and pharmacy data will allow us to create reliable, objective measures of self-monitoring (home glucose monitor test strip use), drug therapy. glycemic control (HbAlc lab results), and diabetes complications (as measured in outpatient visits, emergency room visits, and hospitalizations). Stratifying by type of drug therapy (insulin/combined therapy vs. oral therapy), we will use descriptive analyses, generalized linear mixed models, and proportional hazards models to (1) identify racial differences in self-management practices and diabetes-related health outcomes over time; (2) assess whether African American race is an independent predictor of self-monitoring practice or adherence to drug regimen; and (3) whether there are racial/ethnic differences in the association between self-management and specific clinical endpoints, including glycemic control (HbAlc<8.0) and the incidence of diabetes-related complications over the nine-year study period.